Have you seen that commercial where the woman drops her purse and the guy climbs down the building to get it?. See more at Le Parkour - The French art of Free-Running. Some of the videos don't seem to work, put it is still pretty interesting.
I have found it helpful to do the stretching exercises my physical therapist recommends. Do some core strengthening exercises, such as the ones highlighted at The Mayo Clinic. By keeping your core strong, your back won't put itself in a position to cause that sciatica pain you are having.